refraction of light

Image 1: It enters the eyes after being refracted by the water surface.

Figure 2: After being refracted twice by the glass wall, it enters the eyes.

Figure 3: After the water surface (total reflection), it enters the eyes through the glass wall.

Figure 4: Reflected by the cup wall, and then refracted by the water surface into the eyes.

Such as 5: ...

345 is getting weaker. Usually you can only see 12.

Because two images are generated for two reasons:

1. Different angles or different refractive indexes pass through different refractive surfaces to form images at different positions.

2. The glass wall is thick, and the image will shift after being refracted twice by water glass and glass air.